Buggy code:
public class ProxyManagerImpl implements ProxyManager { private static final String PROXY_SUFFIX = "$proxy" ; private static final Localizer _loc = Localizer . forPackage ( ProxyManagerImpl . class ) ; private static long _proxyId = 0L ; private static final Map _stdCollections = new HashMap ( ) ; private static final Map _stdMaps = new HashMap ( ) ; private final Set _unproxyable = new HashSet ( ) ; private final Map _proxies = new ConcurrentHashMap ( ) ; private boolean _trackChanges = true ; private boolean _assertType = false ; public ProxyManagerImpl ( ) { } public boolean getTrackChanges ( ) { } public void setTrackChanges ( boolean track ) { } public boolean getAssertAllowedType ( ) { } public void setAssertAllowedType ( boolean assertType ) { } public Collection getUnproxyable ( ) { } public void setUnproxyable ( String clsNames ) { } public Object copyArray ( Object orig ) { } public Collection copyCollection ( Collection orig ) { } public Proxy newCollectionProxy ( Class type , Class elementType , Comparator compare ) { } public Map copyMap ( Map orig ) { } public Proxy newMapProxy ( Class type , Class keyType , Class elementType , Comparator compare ) { } public Date copyDate ( Date orig ) { } public Proxy newDateProxy ( Class type ) { } public Calendar copyCalendar ( Calendar orig ) { } public Proxy newCalendarProxy ( Class type , TimeZone zone ) { } public Object copyCustom ( Object orig ) { } public Proxy newCustomProxy ( Object orig ) { } protected Class toProxyableCollectionType ( Class type ) { } protected Class toProxyableMapType ( Class type ) { } private static Class toConcreteType ( Class intf , Map concretes ) { } private ProxyCollection getFactoryProxyCollection ( Class type ) { } private ProxyMap getFactoryProxyMap ( Class type ) { } private ProxyDate getFactoryProxyDate ( Class type ) { } private ProxyCalendar getFactoryProxyCalendar ( Class type ) { } private ProxyBean getFactoryProxyBean ( Object orig ) { } protected boolean isUnproxyable ( Class type ) { } protected Class loadBuildTimeProxy ( Class type , ClassLoader loader ) { } private Proxy instantiateProxy ( Class cls , Constructor cons , Object [ ] args ) { } protected BCClass generateProxyCollectionBytecode ( Class type , boolean runtime ) { } private static String getProxyClassName ( Class type , boolean runtime ) { } private static void assertNotFinal ( Class type ) { } protected BCClass generateProxyMapBytecode ( Class type , boolean runtime ) { } protected BCClass generateProxyDateBytecode ( Class type , boolean runtime ) { } protected BCClass generateProxyCalendarBytecode ( Class type , boolean runtime ) { } protected BCClass generateProxyBeanBytecode ( Class type , boolean runtime ) { if ( Modifier . isFinal ( type . getModifiers ( ) ) ) return null ; <START_BUG> if ( ImplHelper . isManagedType ( type ) ) <END_BUG> return null ; Constructor cons = findCopyConstructor ( type ) ; if ( cons == null ) { Constructor [ ] cs = type . getConstructors ( ) ; for ( int i = 0 ; ( cons == null ) && ( i < ( cs . length ) ) ; i ++ ) if ( ( cs [ i ] . getParameterTypes ( ) . length ) == 0 ) cons = cs [ i ] ; if ( cons == null ) return null ; } Project project = new Project ( ) ; BCClass bc = project . loadClass ( ProxyManagerImpl . getProxyClassName ( type , runtime ) ) ; bc . setSuperclass ( type ) ; bc . declareInterface ( ProxyBean . class ) ; delegateConstructors ( bc , type ) ; addProxyMethods ( bc , true ) ; addProxyBeanMethods ( bc , type , cons ) ; if ( ! ( proxySetters ( bc , type ) ) ) return null ; addWriteReplaceMethod ( bc , runtime ) ; return bc ; } private void delegateConstructors ( BCClass bc , Class type ) { } private void addProxyMethods ( BCClass bc , boolean changeTracker ) { } private void addProxyCollectionMethods ( BCClass bc , Class type ) { } protected boolean allowsDuplicates ( Class type ) { } protected boolean isOrdered ( Class type ) { } private void addProxyMapMethods ( BCClass bc , Class type ) { } private void addProxyDateMethods ( BCClass bc , Class type ) { } private void addProxyCalendarMethods ( BCClass bc , Class type ) { } private void addProxyBeanMethods ( BCClass bc , Class type , Constructor cons ) { } private void copyProperties ( Class type , Code code ) { } private void proxyRecognizedMethods ( BCClass bc , Class type , Class helper , Class proxyType ) { } private static Class [ ] toHelperParameters ( Class [ ] cls , Class helper ) { } private static Class [ ] toHelperAfterParameters ( Class [ ] cls , Class ret , Class beforeRet ) { } private boolean proxySetters ( BCClass bc , Class type ) { } private void proxyOverrideMethod ( BCClass bc , Method meth , Method helper , Class [ ] params ) { } private void proxyBeforeAfterMethod ( BCClass bc , Class type , Method meth , Method before , Class [ ] params , Method after , Class [ ] afterParams ) { } protected boolean isSetter ( Method meth ) { } protected Method findGetter ( Class type , Method setter ) { } private static boolean startsWith ( String str , String token ) { } private void proxySetter ( BCClass bc , Class type , Method meth ) { } private void addWriteReplaceMethod ( BCClass bc , boolean runtime ) { } private static synchronized long nextProxyId ( ) { } protected Constructor findCopyConstructor ( Class cls ) { } private static Constructor findComparatorConstructor ( Class cls ) { }

Fix:
if ( ImplHelper . isManagedType ( null , type ) )